A $7 billion valuation for Twitter isn't crazy. Because if someone were to acquire Twitter, it would have to be for $10 billion. That's not the greatest return on investment for a VC, but it's something.

The Groupon market probably has room for 3-5 players. It would be surprising if it could support 10, but it's a huge market. Merchants are coming back for repeat deals -- you just can't get to Groupon's size doing one deal per merchant. "They're not all pissed."

Horowitz is still happy with his firm's bet on Picplz -- he thinks it could ultimately be a bigger, more important business than Instagram, which has been growing much faster than Picplz. And anyway, thanks to the firm's early bet on Burbn, the startup that pivoted to become Instagram, it still owns 7% of Instagram.

Secondary markets, where people can buy and sell startup shares without much oversight, will probably get some serious scrutiny from the SEC. They're also potentially bad for employees, because they can set unrealistic expectations for what a company -- and therefore, an employee, via their options -- is worth, based on small transactions that the company doesn't have a role in.

Why it's not ideal to be a public company if you're pretty small and don't have a ton of cash: Hedge funds can seriously mess you up, as one tried to do to Opsware, the enterprise software company Horowitz used to run.

Specifically, a firm that was shorting Opsware -- Pequot -- had spread a false rumor that Opsware had lost a big deal with Citigroup, and started trying to spook investors. The stock went down 25%. (That, in turn, could have scared customers, and really hurt the business.) Opsware couldn't really respond, even though there never was a Citigroup deal to be lost in the first place. It didn't cause Opsware to miss the quarter or anything, but it could have, which could have started a downward spiral.

One of many reasons companies should be waiting until they're bigger, have cash, and have a more predictable business before they go public.

Square is doing cool stuff now, but they have to pay the same credit card fees as everybody else. Hypothetically, however, in the future, they could facilitate Square-to-Square payments that are not subject to those fees.

As we noted earlier, the Jambox speaker from Jawbone -- which just raised $49 million, led by Horowitz -- seems to be a big hit. It was outselling rival speakers 10-to-1 at the Apple Store, Horowitz said.

Lastly, Ben really digs this video, the trailer for Glitch -- the first game from Flickr co-founder Stewart Butterfield's new company, Tiny Speck, which Andreessen Horowitz has invested in. Check it out:

Disclosure: Marc Andreessen, co-founder of Andreessen Horowitz, is an investor in Business Insider.